Mixed grain photographic emulsions



March 13, 1951 J, CHECHAK 2,544,640

MIXED GRAIN FHOTOGRAPHIC EMULSIONS Filed June 10, 1949 GELATIN LAYERCONTAINING GRAINLESS 5|LVER IODIDE AND HYDROXY BENZENE REDUCING AGENTGAMMA- PHENYL PROPYL ALCOHOL PARTICLES CONTAINING COUPLER ANDGAMMA-PHENYL PROPYL ALCOHOL PARTICLES CONTAINING COUPLER ANDRED-SENSITIZED SILVER HALIDE 5U FPO RT JONAS J- CHECHAK QM? BY Q YWZIJZQATTORNEYS Patented Mar. 13, 1951 UNITED STATES PATENT OFFICE 254435640MIXED GRAIN PHOTOGRAPHI C EMULSIONS Jonas John Chechak, Rochester, N.Y;, assignor to Eastman-Kodak Company, Rochester, N; Y., a corporationof New Jersey Application-J one 10, 1949, Serial No. 98,290

3 Claims.

This invention relates to color photography and particularly to" mixedgrain photographic emulsions.

Mixed grain photographic emulsion in which amul ticolor'ed image isobtained in a'sin'glee'mulsion layer by a single development step areWell known. Fierke and Ghechak U. S. Patent 2,490,749 granted December6, 1949, describes such process in which the silver halide used as thesensitive material is dispersed or peptized iii z'ei'n' and theze'in-peptiz'ed silver halide together with a color coupler is dissolvedin a liquid solvent such as -phenylpropyl alcohol. and the mixturedispersed in gelatin c'r o.-herhydrophilic colloid. Portions of thesilver halide are preferably optically sensitized so that differentportions of the visible spectrum may be recorded in the emulsion layerto permit formation of a natural color photographic image.

One of the difficulies with mixed grain photographic processes is thatthere is color degradation or color contamination of the emulsion layer.In processes using color couplers in the emulsion layer, a considerableamount of the color contamination is due to the wandering of the activeor coupling form of the oxidized developer; pro duced during thedevelopment of the silver'in one set of particles, through the gelatinand into another set of particles containing a coupler difierent fromthat in the first set. For'example, in the process of the Fierkeand'Chechak Pa tent 2,490,749, the active developer produced in thegreen-sensitive particles begins to couple with the magenta coupler inthose particles but some of it diffuses out of the green-sensitizedparticles before it has had time to couple, travels through the gelatinand enters an adjacent particle containing cyan coupler andred-sensitive silver halide. Cyan dye is thereby produced in theredsensitive particle, even though there has been no exposure of thered-sensitive particle. 4 It is therefore anobje'ct or" the presentinvention to provide a novelmixed-grain photographic material andprocess. A further object is'toproi vide a mixed grain materialcontaining diiierently sensitized silver halide particles associatedwith color couplers, in which color contamination due to wandering ofthe oxidized developer is reduced or prevented. Other objects willappear from the following description of my invention. These objects areaccomplished according to the broader aspects of my invention byincorporating in a layer containing diiierently sensitized silver'halide particles having color couplers associated with them, a materialhaving a very large surface such as grainless silver iodide and anon-color-forming hydroxybenzene reducing' agent. My invention isparticularly useful with a mixedgrain process in which the sensitivesilver halide is contained inparticlesof Y-phenylpropy-l-alcoholcontaining color coupler.

In the accompanying drawing, the'single figure is an enlarged View of aphotographic film made according to m invention.

According to-my invention; there-is-provided a photographic layer ofgelatin or other water'- permeable colloidal material having t'woor morediiiere'ntly color-sensitivephotographic emulsions dispersed therein.Preferably the differently' color sensitive photographic emulsions arecontained in dispersed particles of aliquid solvent containing a colorcoupler. The liquid sol vent should, according to-thepreferredembodiment of my invention,- be a solventfor zei'n' or othermaterial with the vehicle for the" silver halide and a-s'olventfor thecoupler and it should allow adequate optical sensitization of the silverhalide. In addition, it should not interfere with the peptizing actionof 'the-zein or other colloidal material used to disperse the silverhalide.

The sensitive emulsions used in my process are preferably silver bromidepositive type emulsions prepared in a solution of zeih-benzy1 alcohol orother organic'solvent as the peptizi'ng material as described in Lowe U;S. application Ser. No. 47,753, filed September 3, 1948. These emulsionsdiffer from the usual gelatino silver halide emulsions in that theycontain-no water and are compa-iible' with the liquidcoupler solvent tobe used in the process. In the process of the Lowe application, gelatincannot be use'd'as' the peptizing material'because it is insoluble inbenzyl alcohol or other organic solvent and contains a considerableamount of'waterwhich makesit incompatible with the liquid couplersolvent;

When using v-pheny-lpropyl alcohol as-the coupler solvent; a suitableamount of optical sensitizing dye is dissolved in a portion" of the-phenylpropyl alcohol which is-then stirred into thezein-peptizedemulsion. A suitable amount of color coupler is also dissolved in"aportion of Y-phenylpropyl' alcohol and" stirred into the sensitizedemulsion. This produces a sensitized emulsion of silver halidecontaining zein and color coupler in solution" in 'y-phenylpropylalcohol.

The emulsion mixture is then poured slowly into a gelatin solution withstirring to" form a dispersion of v-phenylpropyl alcohol containingcolor coupler, sensitized silver halide" and zein. According to myinventiomthe gelatin solution contains a non-co lor forming' benzenereducing agent and grainless silver iodide. The particle size of thedispersed particles of Y-phenylpropyl alcohol containing color couplerand sensitized silver halide is determined by the amount of dispersingagent used. I prefer particles about 5 to 6 microns in diameter. Thedispersion should not be run through a colloid mill because theparticles are then too finely divided resulting in poor color separationwhen the dispersion is mixed with a differently sensitized dispersion.After the dispersion is firmly set, it is chilled and washed in coldwater to remove unwanted salts and benzyl alcohol. Similar dispersionsare made sensitized to other portions of the spectrum and containingappropriate color couplers and these dispersions are blended to producea mixed grain photographic layer. Two or three dispersions made in thisway may be mixed to form either a two-color or a three-color layer.

The layer made in this Way may be exposed and developed in a primaryaromatic amino color developing solution to produce a multi-color imagein the layer.

Suitable developing agents are diethyl-p-phenylene diamine,dimethyl-p-phenylenediamine, 2- amino-5-diethylamino toluene, andN-ethyl-N- methylsulfonamidoethyl p phenyleneamido d1- amine. In orderto produce satisfactory color density, the developin solution shouldhave a pH of at least 10.5.

The hydroxy benzene reducing agents used according to my inventionshould not couple with the oxidized developer, or if they couple, thecoupled product should be readily soluble so that it washes out of thelayer. The reducing agents which I propose to use are thereforenon-colorforming reducing agents. These include amyl hydroquinone,diamyl hydroquinone, lauryl hydroquinone, heptyl hydroquinone, dioctylhydroquinone, resorcinol, l-hydroxy-B-amino naphthalene-3,6-disulfonicacid and the like. In general, the emulsion layer may contain from 0.02gram to 0.20 gram of reducing agent per square foot of coated emulsionsurface. In the case of using non-difiusing reducing agent such asdiamyl hydroquinone and dioctyl hydroquinone, the reducing agent must bedispersed before addition to the gelatin. For example, a dispersion ofdioctyl hydroquinone is produced as follows:

8.0 g. dioctyl hydroquinone is dissolved at about 60 C. in 8.0 cc.dibutyl phthalate and is run, with stirring, at 40 0., into 54.0 cc. of10% gelatin in water containing 6.4 cc. of a 5% aqueous solution ofalkanol B. By means of a colloid mill, the particle size of thedispersion is reduced until the particles are of the order of 1 or 2microns. The dispersion is then made up to a total weight of 100 g. withdistilled water.

The grainless silver iodide used according to my invention has a verylarge surface and therefore has a strong adsorptive afiinity for theactive oxidized form of the developer. Materials such as activatedaluminum oxide and diatomaceous earth may also be used but I prefer touse grainless silver iodide which can be easily removed duringprocessing of the photographic layer. The silver iodide may be preparedby a simple formula such as the following:

A. 100 cc. of 10% gelatin 10 cc. of 6.8% silver nitrate solution B. 100cc. of 10% gelatin 10 cc. of 6.65% potassium iodide solution Pour Brapidly into A at about 40 C.

The silver iodide should be used in amounts of 0.01 gram to 0.1 gram persquare foot of coated emulsion.

My invention is applicable not only to mixed grain emulsions of the typedescribed in Fierlie and Chechak Patent 2,490749, but also to othertypes of mixed grain emulsions such as those described in Godowsky U. S.application Serial No. 715,605, filed December 11, 1946 and Baines eta1. U. S. application Serial No. 789,294, filed December 2, 1947.

When my invention is used in the preferred form in the mixed grainprocess of Fierke and and Chechak Patent 2,490,759, numerous couplercompounds may be employed. The couplers should have molecular sizes andshapes so that although they are soluble in the -phenylpropyl alcohol orother coupler solvents used, they do not readily difiuse in gelatin andin the dispersion in which they are incorporated.

The following couplers are suitable for use according to the invention.It will be understood that this list is not intended to be exhaustivebut merely to illustrate compounds which may be used.

Couplers producing cyan images 2- [a- (4' -tert.amylphenoxy)butyrylamino] -phe- 5- (p-amylphenoxybenzenesulionamino) -1-naphthol2-chloro 5 (N n-valeryl-N-p-isopropylbenzylamino) -1-naphthol2,4-dichloro-5-palmitylamino-l-naphthol 2-lauryl-4-chlorophenol 2-[a(4-tert.amylphenoxy) butyrylamino] -6- phenylphenol 5-(p-laurylbenzenesulfamido) -1-naphthol Couplers producing magentaimage's l-phenyl-3-palmitylamino-5-pyrazolone 2-cyanoacetylcoumarone-5(N n-amyl-p-sec.-

amylsulfanilide) 2-cyanoacetylcoumarone 5 (N-n-amyl-p-tert.-

amylsulfanilide) 2-cyanoacetylcoumarone 5-(N-y-phenypropyl)p-tert.amylsulfonanilide 2-cyanoacetylcoumarone-5 sulfon-N-p-isopropylphenyl) -N- ('y-phenylpropyl) -amidel-p-laurylphenyl-3-methyl-5-pyrazolone1-phenyl-3-pentadecyl-5-pyrazolone Couplers producing yellow images N-(4 anisoylacetaminobenzenesulfonyl) -N-benzyl-m-toluidine N- (4benzoylacetaminobenzenesulfonyl) N-benzyl-m-toluidine N-(4berizoylacetaminobenzenesulfonyl) N-namyl-p-toluidinew-Benzoylacetylaniline-p-nonyl-sulfonate The following exampleillustrated a method of forming sensitive photographic layers accordingto my invention.

Example 1 (a) To 50 grams of a silver bromide positive type emulsionprepared in a 10% solution of zein and benzyl alcohol as described inLowe U. S. application Ser. No. 47,753, there was added at 50 C. asolution of 7.5 mg. of green sensitizer 3-ethyl-5- (3 ethyl 2 -(3)-benzoxazolylidene) isopropylidenel-rhodanine in 10 cc. ofy-phenylpropyl alcohol. The mixture was stirred for one hour at 50 C. Tothis was added 1.9 grams of magenta coupler,1-phenyl-3-pentadecyl-5-pyrazolone dissolved in 65 cc. of 'y-phenypropylalcohol and stirred for five minutes at 50 C. While stirring well, thisemulsion mixture was then slowly poured into 300 cc. of gelatin solutionat 40 C. to which had been added 7.5 cc. of a 5% solution of sodiumalkyl naphthalene sulfonate (alkanol B). Stirring was continued for fiveminutes at 40 C. The dispersion was firmly set, shredded and washed fortwo hours in cold water to remove soluble salts and benzyl alcohol. Thetotal weight of the dispersion was about 500 grams.

(1)) A second portion of 50 grams of the silver bromide emulsion made asdescribed above was taken and to it was added a solution of 1.25 mg. ofred sensitizer, 3-ethyl-5-[(1-ethyl-2-(1) -B- naphthothiazoly1ider1e)- a-ethylethylidene] 2- (3 fl -hydroxy-B-ethoxy/3-ethoxyethyl-4-oxo-2-thiono 5 thiazolidyldene) 4-thiazolidone) dissolved in 1.3 cc. pyridineand 10 cc. -phenylpropyl alcohol. The mixture was stirred for one hourat 50 C. To this was added 1.9 grams of cyan coupler2-lauryl-4-chlorophenol dissolved in 65 cc. of 'y-phenylpropyl alcoholand stirred minutes at 50 C. While stirring well, the emulsion mixturewas slowly poured into 300 cc. of 10% gelatin solution at 40 C. to whichhad been added 7.5 cc. of a 5% solution of sodium alkyl naphthalensulfonate. Stirring was continued for 5 minutes at 40 C. The dispersionwas firmly set, shredded and washed for 2 hours in cold water to removesoluble salts and benzyl alcohol. The total weight of the dispersion wasabout 500 grams.

A coating was prepared by adding 5.0 grams of dioctyl hydroquinonedispersion and 5 grams of grainless silver iodide emulsion prepared asdescribed above to 150 grams of a 10% gelatin solution and then adding75 grams of dispersion (a) with stirring. To this there was added 75grams of dispersion (b) and the whole was thoroughly mixed. Suitablecoatings were obtained by coating at the rate of 10 grams of emulsion toa 5 x 7 inch plate.

The dried coating was exposed to an image through red and green filters.It is necessary to exclude blue light since the emulsion is sensitive tothe blue region and is intended to record only red and green light. Theexposed layer was developed in the following developing solution.

Grams 2-amino-5-diethylamino toluene hydrochloride 2- Sodium sulfite 2Sodium carbonate Potassium bromide 2 Water to 1 liter.

The mixed grain emulsions made according to my invention may be coatedon transparent, translucent or opaque supports such as glass, celluloseester, or suitably coated paper. A single-layer emulsion containingthree types of dispersed particles may be used or an emulsion layercontaining two types of dispersed particles may be overcoated with asingle emulsion layer containing the third color coupler to produce anatural color image. Suitable filter layers may bused to restrict theeffect of undesired light in the manner Well-known in the art, or afilter dye, for example a yellow filter dye, may be incorporated in theemulsion coating its;lf.

My invention will now be described by refer ence to the accompanyingdrawing. As shown therein, a support In of any suitable material iscoated with a layer of gelatin. ll containng grainless silver iodide anda hydroxy benzene reducing agent. Layer ll contains particles I2 ofcoupler solvent such as y-phenylpropyl alcohol containing coupler andgreen-sensitized silver halide. In the same layer, there are similarparticles l3 of coupler solvent containing coupler and red sensitizersilver halide. The method of exposing and developing this element willbe understood by reference to the specific example above.

,It will b understood that the examples in cluded herein areillustrative only and that numerous variations may be made within thescope of-the appended claims.

I claim:

1'. A light-sensitive layer for producing a colored photographic imageupon exposure and development, comprising a layer of water-permeablecolloidal material having dispersed therein (1) particles of'y-phenylpropyl alcohol containing sensitive silver halide and a colorcoupler, (2) grainless silver iodide and (3) a non-color-forming hydroxybenzene reducing agent.

2. A light-sensitive layer for producing a colored photographic imageupon exposure and development comprising a layer of gelatin havingdispersed therein (1) particles of 'y-phenylpropyl alcohol containingsensitive silver halide and a color coupler, (2) grainless silver iodideand (3) dioctyl hydroquinone.

3. A light-sensitive layer for producing a colored photographic imageupon exposure and development comprising a layer of gelatin havingdispersed therein 1) particles of water-insoluble, developer-permeablecolloidal material containing optically sensitized silver halide and acolor coupler, (2) grainless silver iodide and (3) dioctyl hydroquinone.

JONAS JOHN CHECHAK.

REFERENCES CITED The following references are of record in the file ofthis patent:

. UNITED STATES PATENTS Number Name Date 2,318,597 Davey et a1 May 11,1943 2,490,749 Fierke et al. Dec. 6, 1949

1. A LIGHT-SENSITIVE LAYER FOR PRODUCING A COLORED PHOTOGRAPHIC IMAGEUPON EXPOSURE AND DEVELOPMENT, COMPRISING A LAYER OF WATER-PERMEABLECOLLOIDAL MATERIAL HAVING DISPERSED THEREIN (1) PARTICLES OF$-PHENYLPROPYL ALCOHOL CONTAINING SENSITIVE SILVER HALIDE AND A COLORCOUPLER, (2) GRAINLESS SILVER IODIDE AND (3) A NON-COLOR-FORMING HYDROXYBENZENE REDUCING AGENT.